This invention relates to a land reclamation method which involves the introduction and mixing of a fluid and substances dispersed in air, and the related equipment.
In accordance with the method invented, the land is drilled to the required depth with a probe fitted with at least one radial nozzle, a pipe which supplies the said nozzle with a very high pressure fluid, and a second pipe through which a dry substance mixed with air is conveyed, forced out by the said high pressure fluid, and mixed with the soil.
The said pipes are preferably coaxial, and the high-pressure fluid is conveyed through the inner pipe.
Due to the high speed at which the mixture exits from the probe nozzle, a disintegration and mixing effect is produced which causes the substances required for the treatment to be evenly dispersed in the subsoil layers; as a result, the soil is only treated at the required depth.
The invention is particularly suitable for the reclamation of contaminated soil.
The invention falls into the category of technologies applied to land reclamation, especially for treatment of subsoil layers designed to decontaminate or compact soil so as to create a layer with specific characteristics, such as a given degree of impermeability or the like.
Using the method in accordance with the invention, it is possible to inject into soil, or masses of refuse, substances which, by means of physical action (cementation) or chemical action, can stabilise the mass so that it no longer represents a potential danger.
Cases of land pollution are increasingly frequent, especially close to certain factories or sites used as tips for long periods.
The substances which percolate through the soil and are absorbed and dispersed in the subsoil layers often represent a serious source of pollution, creating problems that are very difficult to solve.
The equipment currently used to reclaim this type of land consists of large helicoid screws fixed to the ends of rods which are inserted into the soil and rotated to mix the soil with substances introduced during the advance of the unit.
This is obviously a very expensive system, whose efficacy is debatable.
For example, with this system it is impossible to treat only one layer of subsoil, e.g. to create an impermeable barrier or to decontaminate a specific layer only.
The method does not allow the areas treated to be vertically isolated so that the treatment only affects one layer of subsoil; the surface soil also has to be mixed, involving a considerable waste of time and energy as well as high costs.
These known methods also present the drawback that they require very high power to mix the deeper soil; large equipment therefore has to be used, but the results can hardly be considered perfect, especially as these helicoids rotate at low speeds because they have to mix huge amounts of soil.
In practice, using known reclamation methods it is impossible to treat a specific layer of subsoil; the whole depth has to be treated because the screw blades obviously have to penetrate all the soil layers, starting from ground level, to reach the zone in question.